Nowadays, an in-cell touch technology has become an object getting the attention of major manufacturers. Well-known manufacturers in the world have put a lot of manpower and resources into research and development, improvement of a rate of qualified product, a patent strategy, and other related work for the in-cell touch technology. As a relative popular field at present, the in-cell touch technology has advantages of making an entire display panel have a higher integration level and making the entire display panel lighter and thinner so as to be in line with the trend that consumers pursue after an electronic product. However, as a newly developed technology, the in-cell touch technology still has many problems including a noise problem due to mutual interference between touch and display, a touch sensitivity problem, a qualified rate of in-cell touch products, and the like.
There exists a structure integrating touch and display in the prior art. FIG. 1 is an equivalent circuit diagram of a touch display structure in the prior art. As shown in FIG. 1, the touch display structure includes output lines 1, data lines 4, and gate lines. A touch display unit 2 is defined by the data lines 4 and the gate lines. The touch display unit 2 includes a fourth switch tube T4, a fifth switch tube T5, a storage capacitor Cst, and a liquid crystal capacitor Clc. Wherein, a gate of the fourth switch tube T4 is connected to a gate line Gn, a first electrode of the fourth switch tube T4 is connected to a node P, and a second electrode of the fourth switch tube T4 is connected to a data line 4. A gate of the fifth switch tube T5 is connected to a gate line Gn-1, a first electrode of the fifth switch tube T5 is connected to an output line 1, and a second electrode of the fifth switch tube T5 is connected to the node P. A first terminal of the storage capacitor Cst is connected to a common electrode Vcom, and a second terminal of the storage capacitor Cst is connected to the node P. A first terminal of the liquid crystal capacitor Clc is connected to the common electrode Vcom, and a second terminal of the liquid crystal capacitor Clc is connected to the node P. A capacitance of liquid crystal which is an anisotropic medium is directly related to an orientation and a spacing d of the liquid crystal molecules. Thus, a spacing d of the liquid crystal capacitor Clc changes when a touch occurs, causing a capacitance of the liquid crystal capacitor Clc to change accordingly. Whereas a capacitance of the storage capacitor Cst will not change. If a voltage written into a pixel in a previous frame of picture is Vp, charges stored in the storage capacitor Cst and the liquid crystal capacitor Clc are Qp=Vp*(CST+CLC), where, Vp is a voltage at the node P, CST is a capacitance of the storage capacitor Cst, and CLC is a capacitance of the liquid crystal capacitor Clc. When the gate line Gn-1 is at a high level, the fifth switch tube T5 is turned on, the voltage Vp at the node P is transferred to a signal processor 3 via the fifth switch tube T5 and an output line 1. The signal processor 3 compares Vp with a reference voltage REF to determine whether a touch occurs at the node P, so that a data line 4 inputs a data signal voltage to a corresponding pixel when the gate line Gn is connected. If a touch does not occur at the node P, a voltage at the node P is the voltage Vp written in a previous frame of picture. If a touch occurs at the node P, considering a case where a change value of the capacitance CLC of the liquid crystal capacitor Clc is ΔCLC, the voltage at the node P changes to Vp′ and Vp′=Vp*(CST+CLC)/(CST+CLC+ΔCLC) due to conservation of charges stored in the storage capacitor Cst and the liquid crystal capacitor Clc. Thus, ΔVp=Vp+−Vp≈Vp*ΔCLC/(CST+CLC)/(CST+CLC), and the sensitivity of a touch function is directly determined by the magnitude of ΔVp. Further, the magnitude of ΔVp is affected by the Vp, so that the sensitivity of a touch function is affected by the Vp. As shown in FIG. 1, the storage capacitor Cst and the liquid crystal capacitor Clc are formed between the node P and the common electrode Vcom, and the node P is connected to both the first electrode of the fourth switch tube T4 and the second electrode of the fifth switch tube T5. The node P is a pixel electrode, thus the voltage at the node P is a pixel voltage.
There exist the following technical problems in the touch display structure in the prior art:
1) Since a display function and a touch function are integrated into a touch display unit, and a change value of the voltage at a terminal of the storage capacitor and the liquid crystal capacitor is related to the pixel voltage when a touch occurs, the sensitivity of a touch function is directly affected by the pixel voltage, thereby reducing the sensitivity of a touch;
2) Since a display function and a touch function are integrated into a touch display unit, a pixel will be affected by a great deal of noise in the output lines during display, thereby reducing the display quality of a picture; and
3) Since a display function and a touch function are integrated into a touch display unit, it must take a part of time to process a touch signal during display of a frame of picture, which will have an influence on a charging rate of a pixel, thereby reducing the display quality of a picture.